The presence of gas or air bubbles in most systems employing flowing liquids is highly undesirable. A particular system of this category is a closed hot water heating system in which the gas, in the form of air bubbles flowing with the water, significantly reduces the efficiency of the system. For example, large commercial buildings generally operate on a border line near the upper limits of what is referred to as a critical condition where there is a need to operate a boiler at a higher temperature than would be required if the gas were not present in the system in order to off-set cold areas resulting from poor liquid circulation and heat exchange. Most buildings as a result of poor design layout of the circuits have particular areas which act as air traps and affect the circulation throughout the entire building. Furthermore, because oxygen is one of the prime causes of rapid corrosion, the air bubbles produce extreme corrosion build-ups at one or more locations along the circuit which provide undesirable restrictions in the pipelines.
The heat exchange properties of the system are dependent on the cleanliness or purity of the water in the system. Most of the elements common to the water can be controlled by chemicals to reduce the rate of corrosive attack. However, the oxygen is the most prominent promoter of electro-chemical activity and therefore, should be reduced or removed from the system.
To further enhance the difficulty, heat when directed at a water containing conduit, will bring about a release of gas bubbles in the flowing medium. These bubbles are in the form of steam and other gases which generally do not condense back to a liquid form although this is dependent on the weight of the converted liquid and the operating temperature which is usually sufficiently high throughout the entire circuit to maintain the gaseous bubbles. The gas behaves in the same manner as does the air in the system in terms of flow restriction, reduced heat transfer and corrosive activity.
The corrosion itself is primarily an electrochemical action which includes the removal of metal from one point in the pipe system and the depositing of the metal along other points of the system. The loss of metal from the first point ultimately results in ruptures of leakages. The deposit at other points results in progressive build-ups and ultimate blockages. Again oxygen is the most prominent agent resulting in the corrosion and should therefore be eliminated as much as possible from the flow. Most systems include local air venting means, however, these are only effective against trapped air and are not effective against the air bubbles which are actually flowing with the water. Therefore, such venting only occurs after there has been a total air blockage in the system and in cases where the amount of air in the system is not sufficient to close off an area, its detrimental effects may not be appreciated although they do exist. This results in unrealized wastage of fuel and poor heat transfer conditions relative to a system in which air is not present.
The air in the system also produces hardships on the pumping means by reducing flow velocity and continuity. From the one end of the system the pump is attempting to force the weight of the water up and over the highest point in the system and from the other end of this system the pump is attempting to pull the water downwardly with the assistance of gravity. However, such pushing and pulling is adversely effected by the stretching of the air in the water. In an air-free circuit the water behaves as an interlocked chain and experiences no such stretching effect. However, this condition rarely exists in practice.
Attempts have been made in the past to provide air gas separators such as that described in Canadian Pat. No. 965,357, issued Apr. 1, 1975. However, these attempts are based on providing a vortex in the fluid passing through the separator to throw the heavier water to the outside as a vortex, thereby separating the gas from the liquid. However, due to the unpredictability of air bubble behavior in a flowing liquid medium such vortex systems are very difficult to control. They are dependent upon flow speeds and vortex force. For instance a vortex separator will not work where the flow speed is not high enough to provide a sufficiently strong vortex to throw the water to the outside. Nor will it work if the flow speed is excessively high because the air bubbles, which may be microscopic in size, do not flow with the liquid medium at flow speeds beyond a certain rate. Therefore, vortex separators have very definite limitations.
The present invention overcomes the above difficulties by providing an anti-vortex gas-liquid separator which is compartmentalized for stabilizing the liquid flow and eliminating high speed streams of gas-carrying liquid for purposes of slowing the liquid flow to the extent that the density effect of the air bubbles in the water provides a natural separation of the gas from the liquid.
The separator comprises an inlet passage opening into a first compartment of increased volume for reducing liquid flow speed. Provided in the first compartment is an impact surface for providing a back pressure on liquid flowing from the inlet passage and for reversing the liquid flow direction. Anti-vortex means is provided for impeding the liquid flow path and for suppressing flow vortex resulting from the reversal in liquid flow direction. The separator includes a second compartment of increased volume for a stable, slow uniform flow of stream-free liquid. The second compartment is separated from the first compartment by the anti-vortex means. A venting outlet for the escape of the separated gas and a liquid outlet in the second compartment for the outflow of gas-free liquid are also provided.